1. Field of the Invention
The present invention relates to a host device which can change a capacity of a memory area, a memory card, a memory capacity changing method, a memory capacity changing program and a memory capacity charge giving/receiving method.
2. Description of the Related Art
Magneto-optical disks such as a CD and a DVD have gained great popularity in recent years. Among such magneto-optical disks, a CD-R and a DVD-R have been widely used as storage devices to record digital data.
For settlement of charges regarding such storage devices, a technology has been disclosed to simplify the settlement of charges by using a prepaid card printed in a self-printing manner (Japanese Patent Application Laid-open No. 2002-109631). A technology has also been disclosed to pay charges for downloading software contents in advance by a prepaid card (Japanese Patent Application Laid-open No. 2001-60286).
Conventionally, when a user buys a CD-R or a DVD-R, the user pays a certain amount of money for one disk regardless of a capacity to be used. For example, in the case of a CD-R capable of saving data of 650 megabytes (abbreviated to MB hereinafter), remaining 550 MB are left unused when data of 100 MB is saved. However, as the user pays for one disk, there is a problem that the user must pay the same amount of money whether data of 650 MB is saved in the CD-R or only data of 100 MB is saved.
There is a similar problem in a semiconductor memory card (abbreviated to “memory card”, hereinafter). As a memory capacity is increased, charges must be paid even for an unused memory area. For example, in the case of a memory card of 512 MB, even if only 128 MB are normally used while remaining 384 MB are unused the user pays for 512 MB to buy the memory card.
Meanwhile, a product adaptable to a memory card such as a digital still camera is equipped with a memory card which is most often small in capacity, e.g., 8 MB or 16 MB, because of costs. In this case, if the amount of data saved in the memory card is increased, the user is required to carry a plurality of small-capacity memory cards. To avoid the trouble of doing so, a frequency of usage of the small-capacity memory cards is reduced, and the memory cards are made disposable, creating a serious environmental problem.